1. Field of the Invention
This invention relates in general to integrated circuits and more specifically to transistors formed over an interconnect layer of an integrated circuit.
2. Description of the Related Art
Transistors formed on a semiconductor substrate are utilized to implement circuitry of an integrated circuit. The size of the transistors, the area of substrate space available, and the interconnect structures (e.g. interconnects and vias) needed for the circuitry limit the circuit density of an integrated circuit.
One type of integrated circuit includes a memory array of magneto-resistive Random Access Memory (MRAM) cells formed above interconnect and insulating layers of an integrated circuit. These cells are coupled to access circuitry formed on the substrate of the integrated circuit. An example of an access circuit is a select transistor utilized for a selective read access of an MRAM cell. Typically, this select transistor is located on the substrate. The path between an MRAM cell and a select transistor includes interconnect structures in the interconnect and insulating layers.
Accordingly, implementing a select transistor on the substrate not only requires the utilization of substrate space, but also the utilization of space in the interconnect and insulating layers. What is desired is an improved integrated circuit that allows for a greater density of circuitry.
The use of the same reference symbols in different drawings indicates identical items unless otherwise noted. FIGS. 1 and 2 are not necessarily drawn to scale.